takeaway: The sartorius plays an important role in stabilizing both the hip and knee. It works both synergistically and antagonistically with the tensor fasciae latae, gracilis, and semitendinosus to achieve these important functions.

Sartorius

Attachments
Origin: Anterior superior iliac spine (ASIS)
Insertion: Medial shaft of the tibia via the pes anserinus
Actions
• Flexes the hip
• Abducts the hip
• Externally rotates the hip
• Flexes the knee
• Internally rotates the knee
Innervation
• Femoral nerve
• L2–L3

The sartorius is a long, slender muscle located superficially on the anterior thigh. It is located directly over the top of the rectus femoris, adductor longus, and vastus medialis muscles. Moving from proximal to distal, this muscle traverses the thigh from a central point on the anterior superior iliac crest (ASIS) medially and distally to the medial portion of the knee. This gives the sartorius a distinctive curved shape as it winds around the front and inside of the thigh.
Often referred to as the “tailor’s muscle,” it is so named for the cross-legged working position used in that profession in which the ankle of one leg rests on top of the knee of the other leg. Achieving this position uses the actions of the sartorius, where the hip flexes, abducts, and externally rotates while the knee flexes to 90 degrees.
Along with the tensor fasciae latae muscle, the sartorius forms an upside down “V” on the front of the thigh. Both muscles cross the hip and knee and work synergistically to flex and abduct the hip. They also work antagonistically, rotating the hip in opposite directions, with the sartorius rotating externally and the tensor fasciae latae rotating internally. This relationship provides control in rotational movements of the hip and knee, such as when planting and pivoting the lower extremity.
The sartorius joins the gracilis and semitendinosus muscles at a common insertion at the pes anserinus. The pes anserinus means “goose foot” and is named for its three-pronged shape. The three muscles converge at the inside of the knee and insert on the medial shaft of the tibia. The sartorius descends from the front, the gracilis from the middle, and the semitendinosus from the back of the thigh. Together they form a tripod of dynamic stabilizers for the medial knee.
Ligament injuries to the underlying medial collateral ligament are very common, particularly when these three muscles are weak compared to the lateral stabilizers of the knee. Excessive tension in the iliotibial band and vastus lateralis muscle may also stress the pes anserinus, leading to generalized medial knee pain, specific trigger points, and eventual problems with patellofemoral tracking.

Palpating the Sartorius

Positioning: client supine with hip externally rotated and knee flexed.  
Standing at the client’s side facing the thigh, locate the anterior superior iliac spine (ASIS) with your fingertips.
Slide your fingertips inferiorly and medially along the lateral edge of the femoral triangle. (Caution: The femoral triangle lies just medial to the sartorius and contains lymph nodes as well as the femoral nerve, artery, and vein. To avoid these structures, palpate lateral to the inguinal crease.
Allow your fingers to remain superficial on the thigh to find the strap-like fibers of the sartorius.
Resist as the client performs flexion and external rotation of the hip to ensure proper location.

Passive Stretching of the Sartorius

Positioning: client prone with knee flexed.
Stand at the client’s side and grasp the leg with one hand while stabilizing the pelvis with the other.
The client remains relaxed as you rotate the hip internally, moving the leg toward you.
Extend the knee as you reach the endpoint of the hip’s internal rotation while maintaining a stable pelvis.
Additional hip extension may be required to achieve a noticeable stretch on the sartorius muscle. This can be achieved by placing a wedge or bolster beneath the client’s thigh, maintaining an extended hip while the hip is internally rotated and the knee is extended.